1. Field of the Invention
The present invention relates to a speed light device particularly for a single lens reflex camera with a built-in automatic winding mechanism.
2. Description of the Prior Art
Recent advances in automation and electronification of cameras have enabled operation of the speed light device and of the film winding and rewinding mechanism built in the camera body to be accomplished by means of a single power source. Many of these automatic cameras are of the the compact type with a lens shutter system. However, single lens reflex cameras with interchangeable lens assemblies using both the speed light device and the automatic winding mechanism usually have these devices mounted on the camera as exclusive accessories in accordance with necessity. In case of a compact camera with the noninterchangeable lens, the photographing lens is fixed on the camera, so that a signal representing the distance from the object can easily be derived from the lens and light adjustment for flash photography is accomplished by means of the distance information. Consequently, the electrical circuitry can be simplified and the number of the parts for the speed light device can be reduced. Thus, even if the speed light device is built in the camera the outer dimension of the camera can be made comparatively small so that cameras with a built in speed light device or built in automatic winding mechanism have been brought into practical use.
On the other hand, in the single lens reflex camera lenses with different focal lengths can be interchangeably used. Each of these lenses involve different distance information so that it is not easy, as in case of the lens shutter camera, to apply the distance information from the lens side into the circuit at the camera side in order to effect flash adjustment. Accordingly, a speed light device for the single lens reflex camera usually requires a computer system. The circuit of this speed light device with the computer system is relatively complicated, and it is necessary to make available the maximum amount of flash light from the light emitting element. Thus, the outer dimension of the speed light device becomes too large to be built in the camera without enlarging the outer dimension of the camera.
Recent advances in miniaturization of electronic circuits have enabled the development of camera circuitry which is quite small. However, although the circuit for the computer speed light device can be made very small, the dimensions of a light emitting element having a large enough capacity for the single lens reflex camera, and the reflector and the main condenser therefor, cannot be made small, so that even if the important parts of the speed light device are contained in the camera body the outer dimension of the camera becomes too large to be used conveniently. This makes ordinary camera operation without using the speed light device troublesome.